DNA From a Shark Tooth Embedded in a Man's Foot for 25 Years Identifies the Culprit

It was unclear what species of shark attacked Jeff Weakley while he was surfing off Flagler Beach, Florida in 1994. Whether it was a tiger shark, bull shark, great white shark, or some other predator didn't matter at the time—his priority was swimming to safety before the shark could take another bite.

Twenty-five years later, the wound on Weakley's right foot has healed, and he's had plenty of time to wonder what exactly bit him on that beach trip. By analyzing a tooth fragment that was lodged in his foot for more than two decades, a team of scientists has finally given him an answer, the Ocala StarBanner reports.

Bits of shark tooth have come loose from Weakley's foot several times since he was attacked in 1994. The third time it happened, in fall 2018, he collected the shard and sent it to the Florida Program for Shark Research, a part of the Florida Museum of Natural History in Gainesville. He had just read an article about the program's work identifying shark species using the DNA from their teeth, and he suspected the team might be able to do the same with his tooth fragment.

His hunch was correct: The scientists analyzed the sample and confirmed that the shark that had bit Weakley a quarter-century earlier had been a blacktip shark (Carcharhinus limbatus). That finding was made possible by years of hard work. Over more than two decades, the program has amassed a database of shark DNA containing reference samples for roughly 70 percent of all known shark, skate, ray, and chimera species. Luck was also on their side: The researchers had feared that Weakley's immune system would have destroyed any DNA in the shark's tooth, but when it arrived at the lab, there was enough to make the identification.

Shark attacks are common in movies and TV, but much less so in real life. You're more likely to be struck by lighting or die from the flu than be the victim of a shark attack. When sharks do bite humans, it's often because they've mistaken them for a prey animal, and they'll usually let the victim go once they've realized their error. This is likely how Weakley escaped his shark attack with his foot mostly intact.

This Smart Accessory Converts Your Instant Pot Into an Air Fryer

If you can make a recipe in a slow cooker, Dutch oven, or rice cooker, you can likely adapt it for an Instant Pot. Now, this all-in-one cooker can be converted into an air fryer with one handy accessory.

This Instant Pot air fryer lid—currently available on Amazon for $80—adds six new cooking functions to your 6-quart Instant Pot. You can select the air fry setting to get food hot and crispy fast, using as little as 2 tablespoons of oil. Other options include roast, bake, broil, dehydrate, and reheat.

Many dishes you would prepare in the oven or on the stovetop can be made in your Instant Pot when you switch out the lids. Chicken wings, French fries, and onion rings are just a few of the possibilities mentioned in the product description. And if you're used to frying being a hot, arduous process, this lid works without consuming a ton of energy or heating up your kitchen.

The lid comes with a multi-level air fry basket, a broiling and dehydrating tray, and a protective pad and storage cover. Check it out on Amazon.

For more clever ways to use your Instant Pot, take a look at these recipes.

At Mental Floss, we only write about the products we love and want to share with our readers, so all products are chosen independently by our editors. Mental Floss has affiliate relationships with certain retailers and may receive a percentage of any sale made from the links on this page. Prices and availability are accurate as of the time of publication.

What Do Pets See When They Watch Television?

In 2012, a television commercial aired in the UK for Bakers dog food that was conceived and produced specifically to attract the attention of dogs. The spot used high-frequency sounds that are inaudible to human ears. In theory, the dog would be so captivated by the advertisement that owners would take note and perhaps purchase Bakers for their next meal.

This didn’t quite work. Many dogs failed to react at all, proving that when it comes to television ads, humans may be more impressionable than canines.

While pets may not be so easily manipulated, they still find the television screen interesting, sometimes reacting to other dogs, animals, sounds, or images. But what is a dog really seeing when they tune in?

When it comes to color, television is no different from reality for a dog. They have dichromatic vision, which means they see the world through the range of two primary colors, yellow and blue. (Humans have trichromatic vision, able to see the full color spectrum.) Cone cells in canine eyes are also believed to blur their sight to a degree. More importantly, dogs process the frame rate, or “flicker fusion frequency,” of screens differently than people. Humans can detect movement at between 16 and 20 frames per second. Dogs need 70 frames per second or more. If they’re looking at an older television, it might resemble a flip book or even a strobe light effect to them. (Modern sets have a faster frame rate, which is why dogs might be more interested in your high-definition television.)

That helps explain the visuals. What about the content? Typically, dogs will react to the same things that would draw their attention in a room—barking, squeaking toys, or commands. In a study published in Animal Cognition in 2013, nine dogs were observed to see if they could pick out the face of another dog—regardless of breed—on a computer screen instead of another animal or a person. The dogs were rewarded with treats with a successful choice. Though the sample size was small, it indicated dogs can recognize other dogs on a screen. (Which you likely already knew if you’ve ever observed your dog suddenly on alert when a canine appears on camera.)

If your dog used to get excited by another dog on television but has since lost interest, it’s possible they simply became desensitized to their appearance, realizing the image in front of them isn’t going to move out of the boundaries of the monitor.

Content unrelated to dogs might not be of much interest. In a 2017 study published in the International Journal of Human-Computer Studies, dogs presented with three different viewing screens didn’t exhibit any particular preference for one over the other. If they were shown three screens at one time, they seemed uninterested in watching anything at all.

The study also noted that dogs had a limited television attention span. Rather than mimic the binge-watching habits of humans, dogs prefer to glance at a screen for a few seconds at a time. But that behavior could also be breed-specific. Dogs bred for hunting might be interested in moving objects, while dogs that rely more on smell might be indifferent.

And what about cats? In a study published in Applied Animal Behaviour Science in 2008, 125 shelter cats were given a television to view for up to three hours a day. The cats were split into five groups and given a variety of programming to watch, from humans to footage of prey to a blank screen. On average, cats spent just 6.1 percent of the observation time watching the screen. When they did, it was mostly to focus on the prey.

Because cats may react to images of birds and rodents on television, owners should avoid letting them watch unattended. You can also secure the set to a wall to make sure they don’t knock it down.

For the most part, dogs and cats are far more interested in what’s going on in the real world compared to what's on TV. We could probably take a lesson from their limited screen time.